1-amino-2-bromo-4-hydroxy-anthraquinone by hydrolysis of 1-amino 2,4-dibrom anthraquinone



Patented July 22, 1952 lif W. Seymour,

. 1 I v This invention relates to the production of 1- amlno-2 brom-4-hydroxy-anthraquinone by the of 1-amino-2,4-dibrom'anthraqui ysis cf 1-amino-2;4-dibromanthraquinone employing boric acid in concentrated sulfuric acid as the hydrolyzing agent. 1

Other objects of this invention will appear from the following detailed description.

We have now found that l-amino-ZA-dibromanthraquinone may be hydrolyzed in an ercient and economical manner to 1-amino-2- brom-4-hydroxy-anthraquinone by reacting 1- amino-2,4-dibrom-anthraquinone for 1 to 3 hours at a temperature of from 130 to 170 0., and preferably, at 150 to 155 0., in solution in 150 to 600% by weight of the anthraquinone compound of concentrated sulfuric acid to which has been added 18 to 70%, preferably 32%, of boric acid on the weight of the anthraquinone compound. When reaction is completed the reaction mixture is cooled to below 100 C., drowned in a large volume of water and then filtered at 60 to 70 C. through a porous stone filter. The press cake of 1-amino-2-brom-4- hydroxy-anthraquinone is resludged in water and then again filtered at a temperature of about 80 C. through the porous stone filter. The press cake here obtained is washed with a 2% aqueous sodium carbonate solution until neutral. The 1-amino-2brom-4-hydroxy-an thraquinone obtained is of excellent purity, and improved yields of 98%, and over, based on the 1-amino-2,4-dibrom-anthraquinone reacted are obtained by our novel process.

In order furtherv to illustrate our invention, but without being limited thereto, the following example is given:

Example ried again with 250 parts by weight of concentrated sulfuric acid and heated for 1 hour at 125 C. The solution obtained is then filtered through a stone filter and the filtrate combined The combined fi1- with the original filtrate.

The press cake remaining is slur- [@Salvin, SummitgfN. J seaward B12195 Cumberland, Md.', assigncrsfto 'l' notation of Americafial corporatio No DrawingflApplication August 29, 1 9.47,

Serial No. .7 ,71 ,3 92[ rotatin (oi. 260- 336) trates aretransferred to a reactor, 35 parts, i. e. 32%, by weight of boric acid are added and the reaction mixture is then heated for 2 hours at 150 C. After the resultinghydrolysis reaction is completed, the reaction mixture is run into 1500 parts by weight of water and the l-amino 2-brom-4 hydroxy anthraquinone precipitates I from solution. The mixture is heated to from about 60 to 70 C. then filtered through a porous stone filter. The press cake obtained is resludged in 800 to 1000 parts by weightof water at 80 C. and refiltered. The press cake of 1- 'amino-2-bromlrhydroxy-anthraquinone which is here obtained is then Washed neutral with a 2% by weight aqueous solution of sodium carbonate. The 1-amino-2-bromi-hydroxy-an- I thraquinone has a purity of 95% and the yield obtained is 98% of theory based on the 1-amino- 2fl-dibrorn-anthraquinone reacted.

The 1-amino-2-brom-4 hydroxy anthraquinone may be employed for dyeing cellulose acetate or other organic derivative of cellulose textile materials in desirable red shades after being suitably dispersed and solubilized. It may also be employed as an intermediate in the production of other valuable anthraquinone dyes.

It is to be understood that the foregoingdetailed description is given merely byway of illustration and that many variations may be made therein without departing from the spirit of our invention.

' Having described our invention, what we desire to secure by Letters Patent is:

1. Process for the hydrolysis of l-amino-ZA- dibrom anthraquinone to 1-amino-2-brom-4- hydroxy-anthraquinone, which comprises adding 13 to of boric acid on the weight of the anthraquinone compound to a solution of 1-' amino-2,l-dibrom-anthraquinone in to 600% by weight of concentrated sulfuric acid and heating the reactants to a temperature of 150 to C. for 1 to 3 hours.

2. Process for the hydrolysis of l-amino-ZA- dibrom anthraquinone to 1-amino-2-brom-4- hydroxy-anthraquinone, which comprises adding 32% of boric acid on the weight of the anthraquinone compound in 150 to 600% by weight of concentrated sulfuric acid and heating the reactants to a temperature of 150 to 155 C. for about 2 hours.

3. Process for the hydrolysis of 1-amino-2A- dibrom anthraquinone to 1-amino-2-brom-4- hydroXy-anthraquinone, which comprises adding 18 to 70% of boric acid on the weight of the anthraquinone compound to a solution of 1- amino-2,4-dibrom-anthraquinone in 150t0 600% by weight of concentrated sulfuric acid and heating'the reactants to 'a temperature of 150 to 155 C. for 1 to3 hours, drowning thereacti on mixturelin water.:- filtering at 60-10-70" resludging'the press cake in water, filtering at about 80 C. and washing the press cake neutral with a dilute aqueous solution of sodium'ca'r- V bonate.

' dibrom-anthraquinone in 150 to=600%=.by weight of concentrated sulfuric acid and heating the re actants to a-temperature of 150 to 155 C for" about 2 hours, drowning the reaction mixture in water, filtering at 60 to 70 C., resludgingjhe press cake in water, filtering at about 80 C. and washing the press cake neutral with a 2% aqueous solution of sodium carbonate.

GEORGE w. SEYMOUR. VICTOR LS.SALVIN. WALTER R. EDWARDS.

REFERENCES CITED I'he f lowing-references are of record in the 'file'ei th-i-spaitenti V UNITED STATES PATENTS Number Name Date 1,798,156 Gube1mann.et a1. 1 Mar. 31, 1931 FOREIGN PATENTS v *Numbe r e Country" Date- 203,083 Germany Oct. 10, 19 087 493,505

Great Britain Dec. 7, 1983 

1. PROCESS FOR THE HYDROLYSIS OF 1-AMINO-2,4DIBROM - ANTHRAQUINONE TO 1-AMINO-2-BROM-4ING 18 TO 70% OF BORIC ACID ON THE WEIGHT OF THE ANTHRAQUINONE COMPOUND TO A SOLUTION OF 1AMINO-2,4-DIBROM-ANTHRAQUINONE IN 150 TO 600% BY WEIGHT OF CONCENTRATED SULFURIC ACID AND HEATING THE REACTANTS TO A TEMPERATURE OF 150 TO 155* C. FOR 1 TO 3 HOURS. 